Engine starter



July 2s, 1936.

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INvgNToR wmv Carrara BY M# ATTORNEY Patented July 28, 1936 ENG STAR iLiborio L. Cure, Ferndale, Mich., assigner of one-half to George E.

Mich.

Gaer, Detroit,

Application .lune 10, 1933, Serial No. 675,308

8 Claims.'

This invention relates to a novel engine starter designed to bring abouta soft engagement between the engine and the motor shaft, to thenyieldingly operate the engine from the motor and to automaticallydisconnect the engine from the motor shaft upon normal starting of theengine as well as upon unexpected reverse rotation of said engine.

Starting arrangements now in Wide use utilize the power of the motor tofirst bring about engagement of a pinion with the teeth of ythe flywheelof the engine and to then turn the flywheel. Attempts have heretoforebeen made to soften the engagement ofthe pinion and ywheel byinterposing springs between the pinion andmeans to bring about thenecessary engagement but these only partially cure the difficulty.

Such prior arrangements are also open to objection, due to the liabilityof breakage of teeth or the springs used to cushion the engagement ofthe pinion and flywheel and to yieldingly drive said wheel, uponbackiiring of the engine.

The primary purpose of this invention is to -overcome the objectionsheretofore existing by bringing the pinion completely into mesh with theywheel teeth before utilizing a substantial part of the power of thestarting motor to'turn the engine, and by providing a connection beopinion and ywheel, but in which the arrangement is such that saidelements are not brought into firm driving engagement until the pinionhas been softly and completely brought into mesh with the ywheel teeth.

45 Still another object of the invention is to improve engine startersof the kind that include a pair ofsleeves in threaded engagement witheach other so that automatic disengagement of the pinion carried by oneof them occurs upon starting s of the engine, by softening the action ofthe pinion in engaging the ywheel teeth and by providing for Vtheautomatic disconnection of the sleeves from the motor shaft upon reverserotation of theengine with the pinion in engagement with the ywheel.

. the shaft of standard electric motor such as used Many further objectsof the invention will appear as a description thereof proceeds withreference to the accompanying drawing in which:

Figure 1 is a longitudinal section of the assembly of the improvedengine starter mounted on for starting purposes.

Figure 2 is a longitudinal section of the arrangement showing the partsin the position they occupy at the time of the turning the crank shaft10` of an engine.

Figure 3 is an end view of the arrangement.

Figure 4 is a fragmentary longitudinal view of a modification. I

Like characters of reference are used through- 15 out to designatecorresponding parts.

Referring to Figure 1, the numeral i indicates a standard electricmotor, such as used for starting an internal combustion engine, while 2indicates the armature shaft thereof. The shaft 2 is reduced in diameteradjacent -the motor providing a shoulder 2a, and is further reduced indiameter adjacent its end providing cylindrical section 2b and a section2c provided with splines 2d.

A key 3 secures a. cone t of suitable angle t shaft 2. The key-Way incone 4 permits said cone to be slidable thereon, and sliding movement isresisted by a spring 6b disposed between the shoulder 2a and said cone,and encircling said 30 shaft.

5 is an externally threaded sleeve, freely rotatable and slidable onarmature shaft and formed to provide a clutch face 5a. Said face ispreferably made of conical form. 35

6 is a drivepinion having teeth to mesh with a part of the engineturning with the crank shaft, such as the flywheel thereof. Said teethare preferably beveled at the meshing end to prevent abutting with theteeth-of the flywheel. Pinion 6` is provided with a conical bore 6a, andis internally threaded to t'the externally threaded sleeve 5.

Suitably secured'to pinion 6 is a brake drumv i. Said drum i may be madeof sheet metal, and pressed upon a. cylindrical portion 6b of said.pinion. The drum is formed to provide a rounded shoulder la.

A clutch facing 8 of suitable material is se- .cured to a' clutch sleeve9,-said clutch sleeve hav- 50 vpreferably such as oomnioniy used to holdengine valve springs in place and the clutch sleeve 9. The springretainer may be held on the shaft by a pin I2 or any other suitablemeans. Spring I0 normally presses clutch sleeve 9 in engagement with thesplined part of shaft 2 4and lightly in contact with clutch face 5a onsleeve 5. Clutch faces 5a are formed of suitable material, and may bemolded of bakelite or thelike. If desired, securing pins 5c may beformed as an integral part thereof.

A resilient brake arm I3 -of suitable pressure having a helical shapeadjacent the end I3a, and a rounded end I3b is secured to motor body Iby bolt I4 and lockwasher I5. The end of said arm bears yieldinguponbrake drum 1 providing resistance tothe free rotation of drive pinion 6,and the rounded end I3b holds. said pinion 6 away from flywheel teethwhen the starter is in its inoperative position. A

In the modification of the invention, illustrated in Figure 4, a motorshaft 2' of uniform diameter beyond the shoulder 2a (Figure 1) is used,and a sleeve I I is keyed thereto, at the end thereof by means of a pinI2'. Said sleeve carries splines that normally engage the splines ofclutch sleeve 9' as illustrated. A spring I0 urges the clutch sleeve 9'into contact with the clutch element 5 of the externally threadedsleeve5 and forces said sleeve into splined engagement with the splinedportion of sleeve II .so that in the illustrated position of the partsthe clutch sleeve 9' is driven by a shaft 2' on rotation thereof. Thevclutch faces may be formed as illustrated in this figure rather than asin Figures l and 2.

Having now indicated the relation of the parts of my invention byreference characters, the operation of the same will be readilyunderstood from the following:

When the electric motor is operated, shaft 2 will rotate clutch sleeve 9with clutch facing 8 at a relatively high rate of speed. In the positionshown in Figure 1, the pressure of spring Ill is light causing saidclutch to slip substantially with respect to screw sleeve 5, causingsaid sleeve 5 to turn slowly and with a yielding or soft drive, thisslow turning causing pinion 6 and drum 'l to advance. The pinion willturn much slower than screw sleeve 5 due to the action of brake arm I3and the engagement of its spiral end I3a with the brake drum. I fresistance is encountered in engaging the teeth of the pinion with theteeth of the flywheel, the clutch will slip until the meshing ends ofthe pinion teeth properly engage the flywheel teeth when furtherrotation of the pinion as a unit with sleeve 5 is arrested. 'Ihe pinionis then rapidly brought into engagement with the flywheel teeth but suchaction is noiseless and smooth due to the fact that the teeth arebrought into mesh by the motor operating 'through a friction clutch theelements of which are in light slipping contact. The pinion 6 willadvance slowly as it engages the teeth of the flywheel without turningthe engine and as the pinion advances, brake drum I slides from beneathbrake arm I3. As its movement continues, conical face 6a. of pinion 6will come in contact with conical face 4a of cone 4, when pinion stopsadvancing. Inasmuch as spring 4b resiliently resists movement of cone 4,the pinion will be brought to a stop smoothly and si1ent1y. When thepinion stops advancing continued rotation of the shaft causes the sleeve5 to move toward the right in Figure 2, gradually compressingcompression spring ID as shown in Figure 2, thereby automaticallyincreasing the pressure on the clutch elements, thus automaticallygradually increasing the torque of motor until the compression andfriction of the engine are overcome at which time it will turn the crankshaft and start said engine. When the engine has started on its ownpower, the pinion is rotated rapidly causing the screw sleeve 5 toretract against shoulder 4d, and the pinion then turned so as to bethrown back against shoulder 5b where the parts are again in theiroriginal positions ready for a repetition of the sequence of operationjust described.

It will be understood that the cone 4 and engaging conical faces 4a and6a serve to frictionally couple the pinion 6 to the motor shaft andcause the compression of the spring IIl to provide a firm engagement ofthe friction clutch elements, only when the pinion is completely inengagement with the flywheel, thus avoiding the use of tooI heavy aspring. The friction clutch elements are intended to hold enough tostart the engine but to slip in case of excessive load such as wouldoccur in case of backring.

It will be noted further that cone 4 centralizes the pinion and supportsit firmly during the time it is turning the engine. This is of greatvalue in maintaining the pitch centers between pinion i and enginemember more accurately, and is more desirable than depending on thescrew sleeve alone to accomplish this.

Should the engine backre, the pinion is rotated rapidly in the oppositedirection on the armature shaft, causing screw sleeve 5 to slide outtoward the end of said armature shaft carrying with it clutch elements 5and 9 until the splines 9b on said clutch sleeve de-mesh from thesplines 2d on armature shaft, allowing screw sleeve 5 and clutchelements 5 and 9 to rotate with the pinion on the smooth portion 2b ofthe motor shaft, so that said shaft may continue its rotation withoutany damage whatever to the parts of the starter.

. It will be understood that when'the clutch sleeve 9a disengages thearmature shaft splines, it stays out of engagement for the duration ofthe reverse pressure. When reverse rotation of the engine ceases thespring I0 automatically i returns the sleeve 9a to its normal positionat which the splines 9b are in engagement with splines 2d on motorshaft. If the ends of said splines contact to prevent the spring I0 fromrestoring the parts to their original condition, rotation of the motorshaft will free the splines `from end contact, the splines 2d on shaft 2being rounded as indicated on the drawings to facilitate the action justdescribed.

What is claimed and desired to be secured by United States LettersPatent is:-

1. An engine starter comprising a motor shaft having a friction clutchelement slidably disposed thereon, spline means to connect said shaftand element, means to resiliently urge said element into engagement withsaid spline means, said last in threaded engagement with each other andslidably disposed on a motor shaft, a friction clutch to connect one ofsaid sleeves to said shaft, engine turning means on the other sleeve, abrake drum on said last named sleeve, a spring arm applying brakingpressure on said drum and formed to provide an inclined shoulderandfurther means non-rotatively secured to said shaft to engage the otherof, said sleeves upon predetermined relative movement of said sleeves tocause rmer engagementof said clutch.

3. An engine starter including a pair of sleeves in threaded engagementwith each other and disposed for slidable endwise movement on a motoishaft, a friction clutch to connect one of said sleeves to said shaft,engine turning means on the other sleeve, means to prevent free unitarymovement of said sleeves when in disengagement with the engine, andmeans yieldably engaging said other sleeve to cause rmer engagement ofthe elements of said friction clutch when said sleeves are in enginestarting position.

4. An engine starter including a motor shaft, a pair of sleeves inthreaded engagement with each other, one of said sleeves being slidablyand rotatively disposed on said shaft and the other having means thereonto engage a part of the engine turning with the crank shaft thereof, afriction clutch coupling said rst named sleeve to said shaft, matchingconical surfaces formed on a member non-rotatively mounted on said shaftand said other sleeve to center said last named A sleeve upon said shaftwhen the means thereon engages said part and to cause rm engagement ofthe elements of said clutch and resilient means to press said surfacesin contact at such time.

5. An engine starter including a motor shaft, having a splined and anunsplined portion, a pair of sleeves in threaded engagementwith eachother and slidably and rotatively mounted on said shaft, and mechanismto cause said sleeves to rotate relative to each other to engage one ofthem with a part of the engine connected for rotation with the crankshaft thereof, said mechanism including friction 'clutch elements tocouple the other of said sleeves to said shaft. one of said clutchelements being carried by said last named sleeve and the other beingnon-rotatively secured to said shaft, a spring to` hold said elements in5 engagement with one of them on said splined portion of the shaft andarranged to permit the last named clutch element to shift to said url.-`splined portion of the shaft and thus become disengaged from said shaftupon reverse rotation of said crank shaft.

6. An engine starter comprising a motor shaft, two sleeves in threadedengagement with each other reciprocably and rotatively disposed on saidshaft, a friction clutch element formed on one of said sleeves, acooperating frictionvclutch element on a splined portion of said shaft,a spring to normally urge said clutch elements into light engagement,teeth on the other of said sleeves to engage a part of the engine tostart the same, 20 and means to yieldingly contact with the last namedsleeve when in engagement with said engine part to cause said firstnamed sleeve and the clutch element carried thereby to move toward itscooperating clutch element and compress said spring to increase thepressure between the clutch elements.

'7. The combination defined in claim 6 in which said shaft is providedwith an unsplined part beyond said sleevesv and clutch elements.

8. An engine starter comprising a motor shaft, two sleeves in threadedengagement with each other slidably and rotatively disposed on saidshaft, teeth on one of said sleeves to engage a part of the engine tostart the same, a pair of friction clutch elements non-rotativelysecured to said shaft at opposite ends of said sleeves, springs pressingsaid clutch elements-toward each other, cooperating clutch elementscarried by. both of said sleeves, and mechanism to cause successiveengagement of said clutch elements whereby both of said sleeves arefrictionally coupled to said shaft.

LIBORIO L. CURCURU.

